As Morosi says, the issue is that Upton has an opt-out clause he could exercise after the season. Upton signed a six-year, $132.75 million deal with the Tigers prior to last season. The former No. 1 pick is enjoying one of the best seasons of his career, as he has 28 home runs and a .913 OPS this season.

If Upton were to opt out of his contract after this season, it would be with the confidence that his new deal would be for more money than the $88 million he is owed through 2021.

The Giants are out of the playoff race and have no use for a rental, so they would only want to acquire Upton if they have a reassurance the outfielder will not opt out of his current deal.